Apparatus for straightening metal by stretching

ABSTRACT

There is described a drive means in an apparatus for straightening a running metal band by exposing it simultaneously to alternating bending and to stretching by a hold-back roll assembly and a drawing roll assembly, in each roll assembly every two successive rolls form a roll pair; each roll pair is driven by a gearing group. Each gearing group is formed of a first differential gearing, a second differential gearing and a regulator gearing. The first differential gearing has two output shafts and a compensating gear housing driven by an input shaft. One output shaft of the first differential gearing is connected directly to one roll of the roll pair, while the other output shaft is connected to the other roll of the roll pair through the second differential gearing. The compensating gear housing of the latter is connected to the regulator gearing which is also coupled to the second output shaft of the first differential gearing. By adjusting the regulator gearing, the transmission ratio of the second differential gearing is changed for thus altering the rpm relationship between the two rolls of the roll pair.

United States Patent [191 Munchbach 1 Dec. 11, 1973 APPARATUS FOR STRAIGHTENING METAL BY STRETCHING [75] Inventor: Curt Munchbach,

Pforzheim-Sonnenberg, Germany [73] Assignee: Irma Ungerer,

Pforzheim Brotzingen, Germany [22] Filed: Oct. 20, 1972 [21] Appl. No.: 299,457

' [30] Foreign Application Priority Data Oct. 21, 1971 Germany P 21 52 496.9

[52] U.S. Cl. 72/205, 72/249 [51] Int. CL. ..B21b 39/08, B2ld H05 [58] Field of Search 72/205, 160, 165

[56] References Cited UNITED STATES PATENTS 3,427,848 2/1969 Gay 72/205 3,626,737 12/1971 Defontenay 72/205 Primary Examiner-Milton S. Mehr Attorney-Edwin E. Greigg [57] ABSTRACT There is described a drive means in an apparatus for straightening a running metal band by exposing it simultaneously to alternating bending and to stretching by a hold-back roll assembly and a drawing roll assembly, in each roll assembly every two successive rolls form a roll pair; each roll pair is driven by a gearing group. Each gearing group is formed of a first differential gearing, a second differential gearing and a regulator gearing. The first differential gearing has two output shafts and a compensating gear housing driven by an input shaft. One output shaft of the first differential gearing is connected directly to one roll of the roll pair, while the other output shaft is connected to the other roll of the roll pair through the second differential gearingfThe compensating gear housing of the latter is connected to the regulator gearing which is also coupled to the second output shaft of the first differential gearing. By adjusting the regulator gearing, the transmission ratio of the second differential gearing is changed for thus altering the rpm relationship between the two rolls of the roll pair.

6 Claims, 6 Drawing Figures 1 4 4 1 J47: m Ju 2 \ll l c: c c

lll f E f5 2] [k 5 k l 19 7 r 2O 3 /IL 16T FATENTED DEC 1 '1 I975 SHEET 2 UF 4 APPARATUS FOR STRAIGHTENING METAL BY STRETCI-IING BACKGROUND OF THE INVENTION This invention relates to an apparatus for straightening a continuously running metal band of indefinite length by stretching and is of the type which has a holdback roll assembly, a mechanism for setting the degree of stretch and a drawing roll assembly, arranged dowstream of the hold-back roll assembly. To each roll pair or each roll group of a roll assembly there is assigned a differential gearing which, on the one hand, is directly connected with one roll or with one roll group and, on the other hand, is coupled through a drive connection with the other roll or the other roll group. The rolls in each roll assembly are grouped together in such a manner that the metal band, as it is trained about successive rolls, follows a tortuous, S-path and thus undergoes alternating bending deformations.

In a known stretch-type straightening apparatus of the aforenoted type, for each two rolls there is provided a differential gearing, the housing of which is rotated by a motor. In case the two rolls rotate with different rpms, a compensation is achieved by the compensating bevel gear. A buildup from roll to roll of the drawing force exerted on the advancing band may occur only if the differential gearing is connected with one directly and with the other roll through a drive connection. The latter is a change speed gearing which increases the direct transmission ratio of 1:1 by the value e 1.: a wherein e is the base of the natural logarithm, I]. is the friction between roll and band surface and a is the looping angle (that is, the angle of circumferential engagement between the band and the roll related to the roll axis). If the aforenoted value, which determinesthe possible incremental drawing factor from one roll to the other as a function of the looping angle and the friction, is exceeded, then slippage will occur not onlyat that roll where the said value is exceeded, but also at adjacent rolls connected to the same differential gearing. Since structurally the looping angles a are given and the selected friction value ,u. is fixed in the formula ep. 0, a a -correction, if required, is not possible. Thus, such a stretch-type straightening apparatus cannot be adapted to operational requirements. In particular, such a stretch-type straightening apparatus cannot be adapted to different moduli of elasticity of different materials and there is no possibility of regulating the adhesion in case of bands which have different surface finish, such as blank, matte, etc., or are provided with a rolled design. Furthermore, in these known stretchtype straightening apparatuses it is not possible to take into account the effect of roll emulsion residues and grease or oil stains on the band or on the rolls. It is also not possible to replace or regrind individual rolls subsequent to damage or wear, since a regrinding would lead to a change in the fixed transmission ratio. Consequently, the rolls have to be reground always by pair and must always have the same final diameter. Also, stretch-type straightening apparatuses of this kind are only poorly adapted for the treatment of very thin metal bands because of the effect of frictional losses in the gearing.

OBJECT, SUMMARY AND ADVANTAGES OF THE INVENTION 7 It is an object of the invention to provide an improved stretch-type straightening apparatus wherein the drive means of the roll assemblies may be adapted rapidly and in a simple manner to the operational requirements and wherein said drive means is unaffected by the efficiency of the gearings.

Briefly stated, according to the invention, the aforenoted drive connection includes a differential gearing, the output rpm of which is alterable by a regulator gearing in accordance with the necessary rpm increase or decrease with respect to the output rpm of the first differential gearing. The said regulator gearing is connected to the compensating gear carrier of the associated differential gearing.

By providing the possibility of regulating the transmission ratio between two rolls of a single roll pair or between two roll pairs, it is possible to accurately adapt the transmission ratio between two roll groups to the modulus of elasticity of the sheet metal band to be treated.

By practicing the invention, it is further possible to adapt the transmission ratio and thus the rpm of the as sociated rolls or roll groups to the adhesion effect of the band surface and to the friction value of the individual rolls as well as to the change in the friction value caused by fouling, wear or regrinding of the rolls. a

It is a further advantage of the invention that the frictional losses in the gearings, which depend upon operational conditions such as starting or braking as well as upon band speed, partial or full load and room temperature, do not affect the accuracy of the values transmitted from the gearing to the rolls according to the setting. These frictional losses burden solely the motor operating the gearings and have no effect on the adhesion values of the individual rolls. By virtue of an automatic or manual adjustmentof the regulator gearing, a decrease of the frictional adhesion caused at high band speeds by an aerodynamic effect and by centrifugal forces imparted on the band may be compensated.

The invention will be better understood, as well as further objects and advantages of the invention will become more apparent, from the ensuing detailed specification of several exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 5 is a schematic view of the entire drive means for a stretch-type straightening apparatus according to the invention; and

FIG. 6 is a schematic illustration of a gearing group corresponding to that illustrated in FIG. 2, but including spur gears.

DESCRIPTION OF THE EMBODIMENTS (input) of which carries a ring gear 16 which meshes with a pinion 17 of a drive shaft 18. The differential gearing 3 is connected directly with the roll 2 by means of a first output shaft 19, while a second output shaft 20 of the differential gearing 3 is connected with the roll I through a drive connection which is formed of two miter gears 21, 22, an intermediate shaft 23 and a drive shaft 24. In order to effect the necessary buildup in the pull exerted on the running band, either the differential gearing 3 or the miter gearings 21 and 22 have a fixed transmission ratio which corresponds to the value e ,u ac

Turning now to FIG. 2, there is illustrated the simplest form of the invention. Accordingly, the gearing group 8 includes, in addition to the first differential gearing 3, a second differential gearing 4 having two inputs and an output. The first input of the second differential gearing 4 is driven by a shaft 24a which is connected, through the miter gearing 22 and the intermediate shaft 23, tothe second output shaft 20 of the first differential gearing 3. The output of the second differential gearing 4 is connected to the roll 1 by a shaft 24b. The second input of the second differential gearing 4 is constituted by its compensating gear carrier 40 which is driven by a regulator gearing 6 (such as a steplessly adjustable P.I.V. gearing) and a stepdown gearing 7 which is connected to the output of the regulator gearing 6. The latter and the gearing 7 are driven by the intermediate shaft 23 of the drive connection 5 by a miter gearing 25. With the aid of the regulator gearing 6 and the after-connected stepdown gearing 7 which is formed as a worm gear with a very large stepdown ratio, in any operational condition of the apparatus, to the differential gearing 4 there may be applied, either automatically or manually, small rpm corrections which correspond to the desired n values. By means of this arrangement it is possible to alter the rpm relationship between the two rolls 1 and 2. Since the output rpm of the regulator gearing 6 is substantially reduced by the stepdown gearing 7, any rpm error in the regulator gearing 6 will have a wholly imperceptible effect on the roll-1, since the additional rpm values generated for the roll 1 by driving the compensating gear carrier 4a are in the order of a few thousandths roll rpm.

Turning now to FIG. 3 there is schematically shown the drive means for a drawing roll assembly formed of four rolls 1, 2, 26 and 27 in an S-arrangement. With the roll pair formed of rolls 1 and 2 there is associated a gearing group 8 that corresponds to that of FIG. 2 and with the roll pair formed of rolls 26 and 27 there is associated a gearing group 9 which is equivalent to the gearing group 8. The driving of the corresponding first differential gearings 3 and 31 of the gearing groups 8 and 9, respectively, is effected through output shafts 18 and 18a of a gearing assembly 33 which is similar to the gearing groups 8 or 9 and which comprises a third differential gearing 10 (similar to the differential gearings 3 or 31), a fourth differential gearing 11 (similar to the differential gearing 4) and, in shunt-connection, a regulator gearing 12 having an after-connected stepdown gearing I3 affecting the compensating gear carrier Illa. The regulator gearing 12 serves for altering the transmission ratio between the two output shafts of the differential gearing Ill and thus also between the drive shafts I8 and Ma. The gearing assembly 33 is illustrated in more detail in FIG. 4. The drive shaft 18 is connected directly with the fourth differential gearing 11, whereas the drive shaft 18a is connected through a miter gearing 32 of 1:1 transmission ratio to the third differential gearing 10. The gearing assembly 33 is driven by a drive shaft 34 through a pinion 35 and a meshing ring gear 36 affixed to the compensating gear carrier 10a of the third differential gearing 10.

FIG. 5 shows a drive means for an entire stretch-type straightening apparatus according to the invention having a drawing roll assembly formed of four rolls ll, 2, 26 and 27 driven by a gearing arrangement identical to that of FIG. 3 and a hold-back roll assembly formed of four rolls 37, 38, 39, 40 driven by a gearing arrangement which is a mirror image of that associated with the drawing roll assembly. Since the structure of the gearing arrangement for the hold-back roll assembly is identical to that associated with the drawing roll assembly, a further discussion of the former is not deemed necessary. The aforenoted mirror image arrangement is required to ensure a buildup of the drawing effect from the roll 37 to the roll 40 in the same manner as in the drawing roll assembly in which the pull on the running band increases from the roll 1 to the roll 27.

The drive means of the entire apparatus is rotated by a common motor 14, the drive shaft 41 of which rotates through a pinion 42 and a ring gear 43, the compensating gear carrier 44a of a third differential gearing 44 which corresponds to the third differential gearing It). The drive shaft 41 also rotates a setting gearing 15 for determining the degree of stretch. The gearing 15 has an output shaft 34 constituting the drive shaft for the third differential gearing 10. The setting gearing l5 effects an rpm increase of the drive shaft 34 with respect to the drive shaft 41 by an rpm resulting in the desired degree of stretch for the band.

Turning now to FIG. 6, there is shown a gearing group 8a for a roll pair formed of rolls 1 and 2. This gearing group corresponds essentially to that shown in FIG. 2, but instead of the miter gearings 211, 22 and 25 there are provided spur gearings 45 and 46 which result in a different spatial arrangement of the differential gearings 3 and 4. In the embodiment shown in FIG. 6, the differential gearing 3 is connected directly with the differential gearing 4 through an intermediate shaft 47 which, by virtue of the spur gearing 46, drives the regulator gearing 6, while the output shaft of the differential gearing 4 rotates through the spur gearing 45, a drive shaft 48 of the roll 1.

That which is claimed is:

l. A drive means for an apparatus for straightening a running metal band by bending and stretching, said apparatus being of the known type that has (a) a holdback roll assembly formed of at least one pair of rolls about which said band is trained in an S-shaped path, (b) a drawing roll assembly disposed downstream of said hold-back roll assembly and formed of at least one pair of rolls about which said band is trained in an S- shaped path, (0) a gearing for setting the degree of stretch between said roll assemblies, comprising a gearing group, one associated with each roll pair and having A. a gearing group input shaft,

B. a first differential gearing having 1. a compensating gear carrier forming an input and driven by said gearing group input shaft, 2. a first output connected with a 1:1 transmission ratio with one roll of the roll pair, 3. a second output, C. a second differential gearing having 1. a first input connected with a 1:1 transmission ratio to said second output of said first differential gearing,

2. a second input formed of the compensating gear carrier of said second differential gearing,

3. an output connected with a 1:1 transmission ratio to the other roll of the roll pair and D. a regulator gearing having 1. an input connected with a 1:1 transmission ratio to said second output of said first differential gearing,

2. an output connected at least indirectly with said second input of said second differential gearing, said regulator gearing adapted to vary the transmission ratio between its input and its output for altering the transmission ratio between the second output of said first differential gearing and the output of said second differential gearing to change the rpm relationship between the two rolls forming a roll pair.

2. A drive means as defined in claim 1, wherein at least one roll assembly is formed of at least two roll pairs each associated with a separate gearing group, comprising a gearing assembly, one associated with each pair of gearing groups and having A. a gearing assembly input shaft,

B. a third differential gearing having 1. a compensating gear carrier forming an input and driven by said gearing assembly input shaft,

2. a first output connected with a 1:1 transmission ratio with one gearing group input shaft,

3. a second output,

C. a fourth differential gearing having 1. a first input connected with a 1:1 transmission ratio to said second output of said third differential gearing,

2. a second input formed of the compensating gear carrier of said fourth differential gearing,

3. an output connected with a 1:1 transmission ratio with the other gearing group input shaft and D. a further regulator gearing having 1. an input connected with a 1:1 transmission ratio to said second output of said third differential gearing,

2. an output connected at least indirectly with said second input of said fourth differential gearing, said further regulator gearing adapted to vary the transmission ratio between its input and its output for altering the transmission ratio between the second output of said third differential gear ing and the output of said fourth differential gearing to change the rpm relationship between the two gearing group input shafts.-

3. A drive means as defined in claim 1, including a stepdown gearing having an input connected to the output of said regulator gearing and an output connected to the second input of said second differential gearing, said regulator gearing being steplessly adjustable.

4. A drive means as defined in claim 2, including a stepdown gearing having an input connected to the output of said further regulator gearing and an output connected to the second input of said fourth differential gearing, said regulator gearing being steplessly adjustable.

5.. In an apparatusfor straightening a running metal band by bending and stretching, said apparatus being of the known type that has (a) a hold-back roll assembly formed of at least one pair of rolls about which said band is trained in an S-shaped path, (b) a drawing roll assembly disposed downstream of said hold-back roll assembly and formed of at least one pair of rolls about which said band is trained in an S-shaped path, (c) first differential gearings, one associated with each roll pair, each first differential gearing being connected to one roll of the associated roll pair directly and to the other roll of the same roll pair by means of a drive connection, the improvement comprising A. a second differential gearing coupled to said drive connection and having a compensating gear carrier and B. a regulator gearing connected at least indirectly to said compensating gear carrier for varying the output rpm of said second differential gearing as a function of the required rpm alteration with respect to the first differential gearing associated with the same roll pair.

6. An improvement as defined in claim 5, including A. means for steplessly varying said regulator gearing and B. a stepdown gearing connected between said regulator gearing and said second differential gearing, said regulator gearing being driven by said drive 

1. A drive means for an apparatus for straightening a running metal band by bending and stretching, said apparatus being of the known type that has (a) a hold-back roll assembly formed of at least one pair of rolls about which said band is trained in an Sshaped path, (b) a drawing roll assembly disposed downstream of said hold-back roll assembly and formed of at least one pair of rolls about which said band is trained in an S-shaped path, (c) a gearing for setting the degree of stretch between said roll assemblies, comprising a gearing group, one associated with each roll pair and having A. a gearing group input shaft, B. a first differential gearing having
 1. a compensating gear carrier forming an input and driven by said gearing group input shaft,
 2. a first output connected with a 1:1 transmission ratio with one roll of the roll pair,
 3. a second output, C. a second differential gearing having
 1. a first input connected with a 1:1 transmission ratio to said second output of said first differential gearing,
 2. a second input formed of the compensating gear carrier of said second differential gearing,
 3. an output connected with a 1:1 transmission ratio to the other roll of the roll pair and D. a regulator gearing having
 1. an input connected with a 1:1 transmission ratio to said seconD output of said first differential gearing,
 2. an output connected at least indirectly with said second input of said second differential gearing, said regulator gearing adapted to vary the transmission ratio between its input and its output for altering the transmission ratio between the second output of said first differential gearing and the output of said second differential gearing to change the rpm relationship between the two rolls forming a roll pair.
 2. an output connected at least indirectly with said second input of said fourth differential gearing, said further regulator gearing adapted to vary the transmission ratio between its input and its output for altering the transmission ratio between the second output of said third differential gearing and the output of said fourth differential gearing to change the rpm relationship between the two gearing group input shafts.
 2. a second input formed of the compensating gear carrier of said fourth differential gearing,
 2. a first output connected with a 1:1 transmission ratio with one roll of the roll pair,
 2. a second input formed of the compensating gear carrier of said second differential gearing,
 2. an output connected at least indirectly with said second input of said second differential gearing, said regulator gearing adapted to vary the transmission ratio between its input and its output for altering the transmission ratio between the second output of said first differential gearing and the output of said second differential gearing to change the rpm relationship between the two rolls forming a roll pair.
 2. A drive means as defined in claim 1, wherein at least one roll assembly is formed of at least two roll pairs each associated with a separate gearing group, comprising a gearing assembly, one associated with each pair of gearing groups and having A. a gearing assembly input shaft, B. a third differential gearing having
 2. a first output connected with a 1:1 transmission ratio with one gearing group input shaft,
 3. a second output, C. a fourth differential gearing having
 3. an output connected with a 1:1 transmission ratio to the other roll of the roll pair and D. a regulator gearing having
 3. a second output, C. a second differential gearing having
 3. an output connected with a 1:1 transmission ratio with the other gearing group input shaft and D. a further regulator gearing having
 3. A drive means as defined in claim 1, including a stepdown gearing having an input connected to the output of said regulator gearing and an output connected to the second input of said second differential gearing, said regulator gearing being steplessly adjustable.
 4. A drive means as defined in claim 2, including a stepdown gearing having an input connected to the output of said further regulator gearing and an output connected to the second input of said fourth differential gearing, said regulator gearing being steplessly adjustable.
 5. In an apparatus for straightening a running metal band by bending and stretching, said apparatus being of the known type that has (a) a hold-back roll assembly formed of at least one pair of rolls about which said band is trained in an S-shaped path, (b) a drawing roll assembly disposed downstream of said hold-back roll assembly and formed of at least one pair of rolls about which said band is trained in an S-shaped path, (c) first differential gearings, one associated with each roll pair, each first differential gearing being connected to one roll of the associated roll pair directly and to the other roll of the same roll pair by means of a drive connection, the improvement comprising A. a second differential gearing coupled to said drive connection and having a compensating gear carrier and B. a regulator gearing connected at least indirectly to said compensating gear carrier for varying the output rpm of said second differential gearing as a function of the required rpm alteration with respect to the first differential gearing associated with the same roll pair.
 6. An improvement as defined in claim 5, including A. means for steplessly varying said regulator gearing and B. a stepdown gearing connected between said regulator gearing and said second differential gearing, said regulator gearing being driven by said drive connection. 